The present invention relates to the mechanical separation of plant stalks into component parts for the individual recovery of same.
Apparatus and techniques for separating plant stalks, such as sugarcane, into individual parts, e.g., epidermis, pith, and rind have been heretofore disclosed in U.S. Pat. Nos. 3,424,611 and 3,424,612 issued to R. B. Miller on Jan. 28, 1969, and U.S. Pat. Nos. 3,567,510 and 3,976,498 issued to S. E. Tilby on Mar. 2, 1971 and Aug. 24, 1976, respectively.
Apparatus and techniques in accordance with the above-mentioned patents of S. E. Tilby have proven highly successful in the separation of plant stalks. Basically, the apparatus and techniques of above-referenced Tilby U.S. Pat. No. 3,976,498 involve a stalk separator comprising a pair of cylindrical feed rolls driven on opposite sides of a stalk-splitting blade. The rollers are resilient and define a nip which captures oncoming chopped pieces or billets of stalk that fall from the lower end of a guide chute, and force such billets against the blade whereupon they are split longitudinally in half. Each billet half is then transferred to a pith-removing station and then, possibly, to an epidermis removing station. At each such station there is disposed a milling roll and an opposing hold-back roll, which rolls are driven in the same direction through their nip but at different speeds. The milling roll is driven at a higher speed and comprises cutting edges which mill the pith (or epidermis) from the rind. The hold-back roll includes rearwardly raked teeth which penetrate the rind to control its travel speed as it passes through the nip. If an epidermis removing station is also employed, the billet half is delivered from the pith removing station along a guide plate to the epidermis removal station.
Although the above-described separator has functioned successfully, certain problems have been encountered. For example, there may occur an occasional tendency for billets to be fed by the feed rolls against the splitting blade in skewed or non-longitudinal orientation. This occurs primarily in connection with shorter billets, i.e., end pieces or stubs of the stalks which are shorter than the normal billet length and are unable to entirely bridge the gap between the lower discharge end of the guide chute and the nip of the feed rolls. As a result, billet-jamming may occur.
Still another problem relates to a tendency for certain types of trash, such as leaves for example, which may be carried along with the billets, to become hung-up on the edge of the splitter blade. Build-ups of such trash require that the separator be shut-down, opened and cleared.
Another problem which has been encountered relates to the pith and epidermis removal stations. The high speed of the milling roll imposes great forces on the billets which must be resisted by the hold-back roll. Despite the presence of the rind-penetrating teeth on the hold-back roll, the latter may, on occasion, lose control of the billet which is propelled forwardly without being fully stripped of its pith (or epidermis).
Still another problem occurs when billets discharged from the pith removal station are fed onto a downstream guide plate, because rind fibers of the billets tend to become hung-up on the leading end of the guide plate. An ensuing build-up of such fibers requires the separator to be shut-down and cleared. This problem has been previously eliminated by the provision of a continuously driven plate-clearing roll which removes such caught fibers, as disclosed in U.S. Pat. No. 4,151,004 issued on Apr. 24, 1979 to Branko Vukelic. Although effective, the clearing roll constitutes still another component in the separator which must be separately installed, driven, and maintained, and thus increases the overall complexity of the machine.
An inconvenience encountered during operation of the separator involves the maintenance of the sharp cutting edges on the blades of the milling roll. When the cutting edges of the blades become dulled, it is necessary that they be reground. Of course after being reground, the cutting blades may be of different dimension and/or shape, and it can thus be difficult to reposition them on the milling roll such that the cutting edges are properly located relative to the billets being treated. This problem is further complicated by the fact that separators of this type may be operated in areas where few skilled workers are available.
Yet another problem involves quick-release journal mounts for the various rotary rolls of the separator, described in afore-mentioned Tilby U.S. Pat. No. 3,976,498. Such a quick-release involves bearing-mounted journals which have tapered ends engaging tapered axial openings of a roll. The journals can each be released from the roll by the removal of a single bolt. Consequently, the roll may simply be dropped-out from between the bearings. It has occurred on occasion that the journals become stuck within the roll, requiring that high pressure grease be fed into the roll opening to release the journals. This procedure is costly and messy and it would be desirable to eliminate the need for same.